Study On Micro - Morphology Of Petal Surface Of Ranunculaceae

Flowers are the typical reproductive organs of angiosperms, and their evolution history play a crucial role in the diversity of angiosperms. The origin and evolution of floral organs has been a long-standed question for the systematic and evolutionary botanists. Ranunculaceae, which links basal angiosperms and core eudicots, has been known well for a high diversity in floral morphological. Therefore, this plant group is ideally suited for exploring the origin and evolution of flowers. In this dissertation, petals including secretory tissue of25species, which belong to22genera,10tribes in Ranunculaceae, were studied to reveal their micro-morphological features. The preliminary results of the research are as follow:(1)By using semi-thin sectioning and paraffin method, the secretory tissue of petal were observed and determined systematically in Ranunculaceae for the first time.(2) Based on the different characteristics and origins in development process petal in Ranunculaceae can be divided into four parts:petal blade part, nectary part, the bulge and its appendages and petiole.(3) The petals epidermal cells in different species in Ranunculaceae were observed and analysed by using scanning electron microscope. According to the characteristics of the morphology, the petals epidermal cells in Ranunculaceae were divided into11types. The results showed us that there were five types of epidermal cells in the petal blade part among all of the species observed, but type1cell is the main types of in this part. There are two main types of nectary secretory cells. Generally the type of nectary secretory cells were similar in each genus. While at the tribe level, the cell type in nectary part were similar in some tribe but differentiated in other tribe. In petals with bulges, the bulge and its appendages generally differentiated into one to three types of epidermal cells. Out of25species observed in Ranunculaceae, the epidermal cell in the bulge and its appendages in21species were type1cell, so type1cell is the main cell types in this part of petals. Petiole cells differentiated into two main types, only cells in Eranthis stellata Maxim is type11, cells in other24species are type10.This is the first time to explore the micro-morphological features of petal epidermal cells among so many species in Ranunculaceae. Distinguishing the different region in petals based on the development process and the different epidermal cell types based on the morphological feature will help us to detective the evolution history of the diversification of petal morphology in Ranunculaceae in the future.